198 FIELD CROPS FOB THE COTTON-BELT 



different breeders. The most important methods fol- 

 low: 



(1) Each year alternate rows in the breeding plot are 

 detasseled and seed yields ascertained from these rows 

 only. This is the method in most common use. 



(2) The first year only a part of each ear is used in plant- 

 ing the breeding plot and no detasseling is done. By 

 harvesting and weighing the grain from each row the 

 breeder ascertains which were the most productive ears 

 that were used in the planting of the breeding plot. The 

 next season the remnants of the best ears only are planted 

 in progeny rows, a number of which are detasseled. The 

 advantage sought by this method is the elimination of 

 the poor-yielding strains so that all fertihzation will come 

 from productive strains. The method is continued year 

 after year, select ears being used from the breeding plot 

 or the general crop for the ear-row test. 



Hugo de Vries stresses the importance of the plot system 

 in corn breeding as a means of maintaining the purity 

 of select strains. His views are given in the following 

 quotation: "In the system of breeding in plots, the prog- 

 eny of each selected ear constitutes a square by itself, 

 and thus at least for the central stalks a high degree of 

 pure fertilization by the other members of the same family 

 is insured. The observed fact of the high degree of in- 

 dividuality of each family, derived from one single ear, 

 seems to point out the desirability of this plot system for 

 the first year of trial on the breeding plot, even if the row 

 system should be kept as the most convenient for the 

 subsequent years of selection." ^ 



243. Harvesting. — Late in the fall when the corn 

 from all of the progeny rows has become thoroughly 

 1 Hugo de Vries, " Plant Breeding," p. 137. 



